/*
The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

P   A   H   N
A P L S I I G
Y   I   R
And then read line by line: "PAHNAPLSIIGYIR"
Write the code that will take a string and make this conversion given a number of rows:

string convert(string text, int nRows);
convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".
*/

class Solution {
public:
    string convert(string s, int nRows) {
        if (nRows <= 1) return s;
        vector<string> lines(nRows, "");
        int rsize = 2*(nRows-1);
        for (int i = 0; i < s.length(); i++) {
            int res = i % rsize;  // 0 - rsize-1
            if (res < nRows) {  // 0 - nRows-1
                lines[res] += s[i];
            } else { // nRows - rsize-1
                lines[rsize-res] += s[i];
            }
        }
        string result("");
        for (int i = 0; i < nRows; i++) result += lines[i];
        return result;
    }
};
